The purpose of this study was to describe the prevalence of total joint arthroplasty (TJA) in Japanese rheumatoid arthritis (RA) patients undergoing conventional drug treatment in a large observational cohort in Japan. A total of 5,177 RA patients were studied for the prevalence of TJA, who were enrolled in the NinJa database during the fiscal year of 2006. The cases of 2,695 RA patients with more than ten years of disease duration were extracted and subjected to further analysis. The prevalence of TJA increased in accordance with the disease duration, and the prevalence was markedly increased after ten years. Among the 2,695 patients with more than ten years of disease duration, 1,431 TJAs were performed in 645 (24.6%) patients. The patients with TJA had higher disease activity than those without TJA. In this cross-sectional study, TJAs were performed in approximately a quarter of the Japanese RA patients with more than ten years of disease duration. The result showed that patients with higher disease activity required TJA.